Near-field scanning optical microscopes (NSOMs) having submicron spatial resolution are physically large and expensive. Such large size and high cost make their use prohibitive in a variety of applications wherein such submicron resolution would be very useful. For example, a very small, inexpensive, high resolution microscope would be useful for remote sensing applications, such as wherein the information desired is a pattern or a change in pattern or shape, or for imaging in hostile environments and monitoring devices/systems wherein the microscope becomes contaminated by radiation, chemicals or organisms and should be discarded thereafter.
One difficulty in the development of a miniature NSOM is providing a suitable xyz stage. In NSOMs, the sample being observed is scanned to create an image. If such scanning is performed via a movable stage, such a stage must be capable of precisely-controlled micron-scale movement in the x-y plane. One such stage has been described by Indermuehle et al. in "Design and Fabrication of an Overhanging xy-Microactuator with Integrated Tip for Scanning Surface Profiling," vol. 43, Sensors and Actuators A, pp. 346-50 (1994).
In addition, the working distance, i.e., the distance between the optical aperture and the sample, is preferably on the order of the size of the aperture, which may be submicron-sized. Thus, the stage must be precisely positionable in submicron-sized increments in the z-plane, as well. One such miniature xyz stage has been disclosed by Fan et al. in "Self-Assembled Microactuated XYZ Stages for Optical Scanning and Alignment," Proc. 1997 Int'l. Conf. Solid-State Sensors and Actuators (Transducers '97), pp. 319-22, 1997. Fan's xyz stage employs sliding/rotating mechanical joints. Such elements may affect repeatability of motion and introduce noise due to friction.
Thus, there is a need for a robust, miniature xyz stage capable of precisely controlled submicron-scale movement.